In recent decades, life expectancy has increased in large part because of significant advancements in treatment for cardiovascular disease and its risk factors including hypertension and diabetes. Recent evidence suggests that these advances may not extend healthy life, especially at older ages. As life expectancy increases, risk of acquiring Alzheimer’s disease and other dementias increases as well. There are also financial implications – spending on individuals with Alzheimer’s and other dementias is higher than the costs of cancer and heart disease combined, and projected to increase considerably in the coming decades as the US population ages.
Treatments to prevent or delay dementia must be a public health and finance priority. With no current treatment, there has been a focus on prevention of dementia through the reduction of risk factors including better treatment and management of health conditions and diseases such as hypertension and diabetes. The potential impact of this on future dementia prevalence must simultaneously account for the dynamic interplay between diseases and importantly, between disease and mortality. Reductions in the prevalence of one risk (e.g. diabetes) impacts the likelihood of other risks (e.g. hypertension) and will likely increase survival into years of life at higher risk of acquiring dementia.
We use a dynamic economic microsimulation model, the Future Elderly Model, to simultaneously investigate these relationships and quantify the impact on future rates of dementia in the US. We assess the effects of hypothetical reductions in diabetes and hypertension compared to a hypothetical treatment that delays the onset of dementia by two-years.
Given the current health status of a nationally representative cohort of Americans ages 51 and 52 in 2010, and current trends in disease over time, an individual who reaches age 65 can expect, on average, to live an additional 21.5 years. His or her lifetime risk of dementia is 34.7 percent and persons who get dementia on average will live with dementia for 5.2 years.
Diabetes and Hypertension
We found that a 50 percent reduction in the risk of acquiring diabetes or hypertension at mid-life or older ages increased life expectancy by 0.36 years. Yet, this progress came at increased risk of acquiring dementia: lifetime risk increased by 0.7 percentage points.
Delaying Dementia by 2 Years
In comparison to reducing risk of diabetes and hypertension, delaying dementia by two-years increased life expectancy by 0.15 years- a smaller improvement – but lifetime risk of dementia was reduced to 29.3 percent.
You can view all of these results and see how the various interventions affect outcomes in the data below.
Gender and Race
At any given age, the risk is higher for women than men, and non-white Hispanics and blacks compared to whites. But both women and men from all racial/ethnic groups benefit from innovations that delay dementia onset.
Reducing diabetes and hypertension are key priorities for improving public health but will not reduce the significance and growing public health concerns of dementia.
The full article is available at the Journal of Gerontology.
Study citation: Zissimopoulos, J. M., Tysinger, B. C., St. Clair, P. A., & Crimmins, E. M. (2018). The impact of changes in population health and mortality on future prevalence of Alzheimer’s disease and other dementias in the United States. The Journals of Gerontology: Series B, 73(suppl_1), S38-S47.